Spent time today collecting data, simulation models & subcircuit data for LTSpice circuit simulation. A filled in form sent to Fairchild Semiconductors gave me a free spice model for a J201 JFET.

I also found some work I had done, modeling the behavior of an audio logarithmic potentiometer. For a 10K resistor, I had measured the resistance between the wiper and one outer lead, dependent on the rotational value. So, to put it in other terms, I found the resistance when the knob was turned all the way down, in the middle, all the way up, and points inbetween.

I spent some time with Mathematica, playing around with fitting functions, and eventually came up with a formula that fit pretty nicely into the plotted resistance points for the 10k resistor I had.

 

It should be noted that manufacturers don't seem to have a standard for printing the carbon trace that makes up the logarithmic nature of the "audio"-log pots, and I measured several potentiometers that displayed varying resistances for a particular rotation.

I did happen to come across (online) several simulation-ready models that can be used in LTSpice, and which I intend on finding out exactly how they work.

8:30PM - 12:30AM (4HRS)